The present invention relates to an image transfer apparatus that displays an image on a transmission type image display means (device) for displaying the image based on supplied image data, for example, an image which is digitally recorded by a digital still camera (DSC), a video camera, a PC (personal computer) or the like on a transmission type liquid crystal display (LCD) constituted by a liquid crystal display device and with using the display image and transfers the image to (forms an image on) a photosensitive recording medium such as an instant photographic film on which a latent image is formed by exposure and color is developed by development.
Various examples of conventionally known method for transferring, or recording a digitally-recorded image to or on a recording medium include an ink jet system using a dot-type printing head, a laser recording system, and a thermal recording system.
A printing system like the ink jet system has various problems. For example, printing takes time, ink is likely to cause clogging, and precision printing results in the printed sheet being moistened by ink. The laser recording system involves an expensive optical component such as a lens, resulting in high apparatus cost. Further, the laser recording system and the thermal recording system require considerable power consumption and are not suited to be carried about.
Thus, generally speaking, the transfer apparatuses using these systems, in particular, the ones using the ink jet system have a problem that the more precise the apparatus is, the more complicated the driving mechanism and the control mechanism become, as well as the larger and the more expensive the apparatus become, and printing takes a lot of time.
In this regard, JP 10-309829 A, JP 11-242298 A, JP 2000-502555 A, and the like disclose transfer apparatuses of the type in which a display image is formed on a photosensitive recording medium like an instant film by using a liquid crystal device, thereby achieving simplification in structure and cost reduction.
The electronic printer disclosed in JP 10-309829 A is capable of copying the display screen of a liquid crystal display on a photosensitive medium to produce a hard copy of a quality equal to that of a photograph. However, in order to copy the display screen of the liquid crystal display on the photosensitive medium in this electronic printer, an optical component such as a rod lens array is used to be arranged between the display screen of the liquid crystal display and the photosensitive medium, and there is a problem that the optical component is rather expensive. Further, a predetermined distance (total conjugate length) is required between the liquid crystal display and the photosensitive medium. In the example shown, there is a problem that the requisite distance takes 15.1 mm.
In the case of the transfer apparatus disclosed in JP 11-242298 A, there is no need to use an expensive optical component such as a lens or to secure an appropriate focal length. Thus, as compared with the conventional transfer apparatuses, a further reduction can be achieved in terms of size, weight, power consumption, and cost.
In this transfer apparatus, as shown in FIG. 42, a photosensitive film 400 is closely attached to the display surface of a transmission type liquid crystal display (hereinafter referred to as LCD) 300, and a light source (back light 100) provided on the opposite side of the LCD 300 with respect to the photosensitive film 400 is turned on. That is, a fluorescent lamp 101 is switched on to turn on the back light, whereby the image displayed on the LCD 300 is transferred to the photosensitive film 400.
Here, as shown in FIG. 42, the LCD 300 is constituted by a polarizing plate 301 on the display surface side, a glass substrate 302, a liquid crystal layer 303, a glass substrate 304, and a polarizing plate 305 on the back light 100 side.
In addition, as shown in FIG. 43, the publication discloses, as another embodiment, a transfer apparatus in which a lattice 200 for suppressing diffusion of light from the back light 100 to approximate the light to parallel rays is provided between the back light 100 and the LCD 300, and a spacer 201 constituted of a rectangular hollow pipe is provided between the lattice 200 and the LCD 300.
With such a structure, an image of a frame of the lattice 200 (a shadow due to the frame) is prevented from being taken by the photosensitive film 400, thus improving clarity of an image formed on the photosensitive film 400 to a satisfactory degree from the practical point of view without providing an optical component or securing an appropriate focal length.
Incidentally, in the transfer apparatus shown in FIG. 42, thickness of the LCD 300 (total thickness of the LCD 300), that is, total thickness of the polarizing plate 301 on the display surface side, the glass substrate 302, the liquid crystal layer 303, the glass substrate 304, and the polarizing plate 305 on the back light 100 side is 2.8 mm, and a screen of the LCD 300 displayed with a dot size of 0.5 mm is transferred to the photosensitive film 400. In this case, it is proposed that the distance between the LCD 300 and the back light 100 be enlarged to a degree in which blurring of an image to be transferred is not visually recognized.
Further, in the transfer apparatus shown in FIG. 43, there is provided a 5 mm lattice 200 with a thickness of 10 mm to prevent diffusion of the light from the LCD 300, and a 20 mm spacer 201 is arranged between the lattice 200 and the LCD 300. Further, the LCD 300 and the photosensitive film 400 are closely attached together to effect image transfer without involving blurring (unclarity) of the image.
In this case, an image displayed with a dot size of 0.5 mm originally set is transferred to a surface of the photosensitive film 400 with an enlarged dot size of up to 0.67 mm, which means an enlargement by approximately 0.09 mm on one side, and yet the image obtained is satisfactory from the practical point of view.
In addition, JP 2000-502555 A discloses an electronic still camera having a printing capability. This electronic still camera is capable of displaying (photographing) an image on an LCD panel, adjusting an image characteristic of the displayed (photographed) image, if necessary, and then projecting the image on an instant film via a projection optical system, thereby printing the image.
Incidentally, in the transfer apparatus disclosed in each of the above-mentioned publications, an image displayed on an LCD panel can be transferred to a photosensitive film. In order to make such a transfer apparatus practical, it is necessary not only to eliminate blurring of an image to be transferred and further increase clarity but also to make a structure of the apparatus compact, simple and low-cost.
For example, a transfer apparatus disclosed in JP 11-242298 A (see FIG. 43) can improve clarity of an image formed on the photosensitive film 400 to a satisfactory degree from the practical point of view. However, there still remains a shadow due to the framework of the lattice 200 on a transferred image.
In addition, in recent years, screens of LCDs have progressed in terms of definition and LCDs with an increased number of pixels, that is, a smaller dot size, are being commercialized. For example, as LCDs using low-temperature polysilicon type TFTs, UXGA (10.4 inches; 1200×1600 pixels), XGA (6.3 and 4 inches; 1024×768 pixels) are on the market.
Thus, if the LCD with such a high-definition screen is applied to the above-mentioned transfer apparatus, the shadow due to the framework of the lattice 200 is more conspicuous. It is possible to enlarge a distance between the LCD and a photosensitive film to a degree of making this shadow unclear. However, in this case, an image to be transferred may become unclear as well.
In addition, a spacer 201 is used so as to make the shadow due to the framework of the lattice 200 less conspicuous as much as possible. However, since the thickness of the spacer 201 is approximately 20 mm according to the publication, there is a limitation in realizing a thin, small and light image transfer apparatus.
In addition, an attempt to apply the LCD with such a high-definition screen to the transfer apparatus disclosed in JP 11-242298 A would lead to the following problem. In the case of UXGA, the dot size of each of the RGB pixels is approximately 0.04 mm on the shorter side. As described above, in a state in which enlargement in dot size occurs as in the transfer apparatus disclosed in the publication, it tends to be impossible to transfer an LCD image of such a minute dot size to a photosensitive film with satisfactory clarity in a condition in which the dots of the RGB pixels are clearly distinguishable from each others.
In addition, in the transfer apparatus disclosed in the publication, the back light 100 and the LCD 300 are required to be spaced apart from each other in order to maintain clarity without causing blurring of an image to be transferred to the photosensitive film 400. Thus, the above-mentioned LCD with a high-definition screen must have an increased distance from the back light 100. For example, in the transfer apparatus as shown in FIG. 43, thicknesses of the lattice 200 and the spacer 201 provided between the back light 100 and the LCD 300 are required to be increased. Therefore, it is impossible to realize a compact structure with the thickness of the transfer apparatus reduced.
Further, in the transfer apparatus disclosed in JP 11-242298 A, image transfer is effected, with the liquid crystal display (LCD) 300 and the photosensitive film 400 being closely attached together, to prevent blurring (unclarity) of the image and to obtain an image satisfactory from the practical point of view. It is to be noted, however, that exposure of a display image on the LCD 300 to the photosensitive film 400 being closely attached together involves the following problems.
First, as shown in FIG. 42, on the outermost surface of the LCD 300, there is arranged a film-like polarizing plate 301, which is closely attached to the photosensitive film 400 during exposure. When the photosensitive film 400 is moved to perform a post-processing, the photosensitive film 400 and the polarizing plate 301 are rubbed against each other to thereby flaw the film-like polarizing plate 301, and the flaw on the polarizing plate 301 is transferred to the photosensitive film 400. Further, this flaw causes scattering of light, resulting in deterioration in the image quality.
To cope with this, it might be possible for the polarizing plate 301 and the photosensitive film 400 to be closely attached together during exposure and slightly spaced apart from each other when the photosensitive film 400 is moved. For this purpose, however, it would be necessary to newly provide, apart from the photosensitive film 400 moving mechanism, a mechanism for effecting close attachment and detachment of the photosensitive film 400, which is contradictory to the requirement for reduction in cost and size and the like.
Further, generally speaking, a photosensitive film, for example, an instant film, which is most conveniently used, is kept in a lightproof case until it is loaded in a transfer apparatus. Since this lightproof case is equipped with an opening frame somewhat larger than the film, the following procedures must be followed before the photosensitive film can be brought into close contact with the polarizing plate.
That is, first, prior to exposure, one sheet of photosensitive film is taken out singly from the lightproof case, and brought into close contact with the surface of the polarizing plate on the surface of the LCD. In this condition, exposure is performed, and, after the completion of the exposure, the photosensitive film is separated from the polarizing plate surface, and moved for a processing (in the case of an instant film, a processing liquid tube provided in the photosensitive film is pushed open).
These procedures must be repeated for each sheet of photosensitive film. In particular, separating the photosensitive film from the polarizing plate surface does not square with automation (or mechanization).
Moreover, there is also a problem of scattering of light on the surface of the LCD. That is, usually, the transmission type LCD has a structure for holding a liquid crystal layer with a glass substrate and a polarizing material from both sides thereof. Then, processing such as matting (roughening) is applied to the surface of the LCD, that is, the surface of the polarizing material in order to prevent reflection of external light so as to facilitate observation by an observer.
Here, methods that are usually used as the above-mentioned matting processing include a method of forming unevenness on the surface of the polarizing material (polarizing film) using a mechanical or chemical method, or a method of forming unevenness on the surface of the polarizing material by adding transparent particulates of polyester resin, polyurethane resin and the like to the outermost layer thereof. However, since the transparent particulates and the polarizing material have different optical characteristics, that is, different refractive indexes from each other, and the surface of the polarizing material becomes uneven, light emitted from the polarizing material has a high degree of scattering.
Such an LCD is preferable when it is directly observed. However, as described above, if an image displayed on the LCD is transferred to a photosensitive recording material, there is a problem that clarity of the transfer image is low.
The same problem is found in the electronic still camera having the printing capability disclosed in JP 2000-502555 A. That is, this camera is constituted so as to project an image displayed on an LCD panel onto an instant film and expose the instant film to light via a projection optical system. However, since the display image to be projected is an image displayed on the LCD panel having an ordinary polarizing film subjected to the above-mentioned matting processing, the exposure is performed by light with strong scattering. Thus, it cannot be denied that clarity of the image decreases.